1. Field of the Invention
The present invention relates to a developing apparatus which is used in an electrophotographic copying machine or the like, and more particularly to a developing apparatus in which the amount of developer to be conveyed on the surface of a developing roller is regulated by a regulating member so that the developer is formed into a layer of a predetermined thickness for developing a latent image formed on an image-holding means such as a photosensitive drum or the like.
2. Description of the Prior Art
A developing apparatus which is used in an electrophotographic copying machine or the like is disclosed in, for example, Japanese Laid-Open Patent Publication No. 61-267771. The developing apparatus disclosed in the above patent publication includes a developing roller which delivers developer to an image-holding means such as a photosensitive drum or the like, and a supply roller disposed in contact with the developing roller for supplying developer to the developing roller. The axis of the supply roller is positioned lower than that of the developing roller, while the top of the supply roller is positioned higher than that of the developing roller.
In such a developing apparatus, the developer delivered to the supply roller is conveyed on the surface of the supply roller, and falls from the top thereof onto the developing roller positioned lower than the supply roller. The developer that falls down onto the surface of the developing roller is conveyed on the surface thereof toward the image-holding means by the rotation of the developing roller. The amount of the developer to be conveyed on the developing roller is regulated by a regulating member disposed above the developing roller, so that the developer is formed into a thin layer to be conveyed on the surface of the developing roller. Then, the developer in the form of a thin layer develops a latent image formed on the image-holding means. On the other hand, the regulating member prevents further transportation of some of the developer when it regulates the amount of the developer to be conveyed on the developing roller as described above. Accordingly, the developer which is kept back by the regulating member accumulates on the upper part of the surface of the developing roller, so that there is a possibility that the accumulated developer will collect into a lump (i.e., blocking of the developer).